Sidelink Synchronization Blocks With Multi-Point LBT Access
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In sidelink communications, listen-before-talk (LBT) operations for sidelink synchronization signal blocks (S-SSB) face challenges due to high likelihood of failure, particularly when transmission is initiated at slot boundaries, leading to degraded synchronization and communication performance, especially in unlicensed spectrum.
Innovation Solution
The proposed solution involves increasing the number of candidate starting points for LBT operations within a slot and allowing for flexible transmission strategies based on LBT success or failure at different points, including repetition and dropping of S-SSB parts, to enhance channel access opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LBT operation is performed at slot boundaries for S-SSB transmission, then transmission timing is simplified and aligned with frame structure, but channel access success rate deteriorates due to high collision probability
Solution Approach 1:
The S-SSB transmission opportunity is segmented into multiple candidate starting points within a slot (e.g., symbol 0, symbol 1, symbol 2, etc.). Instead of attempting a single LBT at slot boundary, the system divides the transmission attempt into multiple sequential opportunities, each with its own LBT operation. This segmentation transforms a single high-collision event into multiple lower-collision events, improving overall access success rate while maintaining structural simplicity.
Solution Approach 2:
The system dynamically selects which candidate starting point to use based on LBT outcomes. If LBT succeeds at an earlier candidate point, transmission proceeds from that point. If LBT fails, the system dynamically moves to the next candidate starting point. This dynamic adaptation allows the system to respond to real-time channel conditions while maintaining the simplified slot-boundary alignment structure.
2Reliability
If multiple candidate starting points are introduced for LBT operations, then channel access opportunities increase and success rate improves, but system complexity increases due to additional LBT operations and decision logic
Solution Approach 1:
The candidate starting points and their associated LBT operations are pre-configured and predetermined. The system prepares multiple LBT opportunities in advance at specific symbol positions within the slot, rather than making complex real-time decisions about when to attempt transmission. This preliminary structuring reduces runtime complexity while maintaining multiple access opportunities.
Solution Approach 2:
The system changes the parameter of transmission starting position from a single fixed slot boundary to multiple configurable symbol positions within the slot. By adjusting this parameter (the set of candidate starting points), the system can optimize channel access probability without fundamentally changing the LBT mechanism itself, thus managing complexity through parameter optimization rather than structural complexity.
3Reliability
If S-SSB transmission is dropped or repeated based on LBT outcomes at different points, then synchronization reliability improves, but transmission efficiency deteriorates due to potential repetitions and drops
Solution Approach 1:
The system performs LBT operations at multiple candidate starting points (excessive action) to ensure high probability of finding an available channel, even though only one successful transmission is ultimately needed. This excessive LBT sampling at predetermined points ensures synchronization reliability by increasing the likelihood of finding an open channel, while the partial transmission (only from the successful LBT point) maintains efficiency by avoiding unnecessary repetitions.
Data Source
AI summary
Presented are systems, methods, apparatuses, or computer-readable media for performing listen-before-talk (LBT) operations in sidelink communications. A wireless communication device may perform a LBT operation with respect to a sidelink synchronization signal block (S-SSB) having a first part and a second part. The first part may repeat one or more symbols from the second part according to a configuration of the second part. The wireless communication device may determine a failure in the LBT operation at a first point in the S-SSB. The wireless communication device may determine a success in the LBT operation at a second point of the S-SSB subsequent to the first point. The wireless communication device may transmit, responsive to the success, at least a portion of the S-SSB mapped to one or more time-domain resources starting from the second point.